• KSBB Journal
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• v.4 no.3
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• pp.271-275
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• 1989

Batch growth of plant cell suspension cultures of Thalictrum rugosum was studied to clarify the kinetic behaviors. It was found that the product formation was growth associated. The specific growth rate was $0.20-0.25\;day\;^{-1}$/TEX> at the growth phase and the FW/DCW ratio was an interesting parameter which represented the status of the cells or the status of sugar concentration. The cell yield was 0.36 g cells/g sugar. The maximum berberine level was 139 mg/L of which 120 mg/L was intracellular. In terms of the specific content of berberine, the product was 1.10% of dry cell weight. At the growth phase, the relationship between the specific growth rate and sugar concentration was described well by Monod kinetics.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.7-13
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• 2002

The removal efficiency of heavy metals by chitosan complex isolated from biological industrial waste was investigated through laboratory experiments. The results of the study are as follows. The adsorption kinetics of heavy metals were reached the equilibrium adsorption in approximately 30 minutes and the removal efficiency were showed 70.7～97.4%. The effect of temperature on heavy metals adsorption by chitosan complex shows that as the temperature increased, the amount of heavy metals adsorption per unit weight of chitosan complex increased. The correlation between amount of heavy metals adsorption per unit weight of chitosan complex and temperature were obtained through the coefficient of determination($R^2$). $R^2$ values were 0.75(p<0.05), 0.99(p<0.05) and 0.98(p<0.05) in Hg, Mn, and Zn, respectively. The injected chitosan complex in which 0.1 g was adsorpted highly and the removal of heavy metals was found to have the best removal efficiency A linearized Freundlich equation was used to fit the acquired experimental data. As a result, Freundlich constants, the adsorption intensity(I/n) was 0.5564, 0.4074, 0.5244 on the Hg, Mn, Zn, respectively And the measure of adsorption(k) was 2.2144, 1.6963, 2.0792 on the Hg, Mn, Zn, respectively. So, it was concluded that adsorption of heavy metals by chitosan complex is effective.

• Journal of Pharmaceutical Investigation
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• v.30 no.3
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• pp.207-211
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• 2000

The objective of this work is to investigate the effect of molecular weight of poly(ethylene oxide) (PEO) and release medium on the release of nifedipine (NP) from PEO tablets containing NP and to get some mechanistic insights into the release of NP. The tablets containing NP were prepared by direct compression, using a flat-faced punch and die. The molecular weights of PEOs used were 200K, 900K, 2000K and 7,000K. The release kinetics were studied for 24 hours in aqueous ethanol solution, using a dissolution tester at $36.5^{\circ}C$ and 100 rpm. Drug release rate increased, as the concentration of ethanol in the dissolution medium increased, due to the increased solubility of NP. As the molecular weight of PEO increased, release rate decreased, due to the slower swelling and dissolution of PEO. The power values obtained by fitting data to the power law expression $(M_t/M_{\infty}=kt^n)$ indicated that, at low ethanol concentration, the release of NP is governed by anomalous diffusion. However, as the ethanol concentration increases, diffusional release becomes to prevail over anomalous or zero-order release. Overall, these results provided some insights into the release of NP from PEO tablet.

• Fibers and Polymers
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• v.5 no.4
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• pp.289-296
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• 2004

The kinetic parameters, including the activation energy E, the reaction order n, and the pre-exponential factor Z, of the degradation of the copolymers based on the poly(L-lactide) (PLLA) or poly(p-dioxanone-co-L-lactide) (PDO/PLLA) and diol-terminated poly(ethylene glycol) (PEG) segments have been evaluated by the single heating methods of Friedman and Freeman-Carroll. The experimental results showed that copolymers exhibited two degradation steps under nitrogen that can be ascribed to PLLA or PDO/PLLA and PEG segments, respectively. However, copolymers exhibited almost single degradation step in air. Although the values of initial decomposition temperature were scattered, copolymers showed the lower maximum weight loss rate and degradation-activation energy in air than in nitrogen whereas the higher value of temperature at the maximum rate of weight loss was observed in air.

• Journal of the Korean Wood Science and Technology
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• v.47 no.2
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• pp.221-228
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• 2019

This study reports the performance of urea-formaldehyde (UF) resins prepared at two different low formaldehyde/urea (F/U) mole ratios with different numbers of urea addition during synthesis. The second or third urea was added during the synthesis of UF resins to obtain two different low molar ratios of 0.7 and 1.0, respectively. The molecular weights, cure kinetics, and adhesion performance of these resins were characterized by the gel permeation chromatography, differential scanning calorimetry, and tensile shear strength of plywood, respectively. When the number of urea additions and F/U molar ratio increased, the gelation time decreased, whereas the viscosity and molecular weight increased. Further, the UF resins prepared with the second urea and 1.0 molar ratio resulted in greater activation energy than those with third urea and 0.7 molar ratio. Tensile shear strength and formaldehyde emission (FE) of the plywood that bonded with these resins increased when the number of urea additions and molar ratio increased. These results suggest that the UF resins prepared with 0.7 molar ratio and third urea addition provide lower adhesion performance and FE than those resins with 1.0 mole ratio and the second urea addition.

• Corrosion Science and Technology
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• v.22 no.6
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• pp.478-483
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• 2023

This study examined the corrosion behavior of bimetal materials composed of Fe-Ni alloy and Fe-Ni-Mo alloy, both suitable for use in electromagnetic switches. Electrochemical polarization and weight loss measurements revealed that, in contrast to Fe-Ni alloy, which exhibited pseudo-passivity behavior, Fe-Ni-Mo alloy had higher anodic current density, displaying only active dissolution and greater weight loss. This indicated a lower corrosion resistance in the Fe-Ni-Mo alloy. Equilibrium calculations for the phase fraction of precipitates suggested that the addition of 1 wt% Mo may lead to the formation of second-phase precipitates, such as Laves and M₆C, in the γ matrix. These precipitates might degrade the homogeneity of the passive film formed on the surface, leading to localized attacks during the corrosion process. Therefore, considering the differences in corrosion kinetics between these bimetal materials, the early degradation caused by galvanic corrosion should be prevented by designing a new alloy, optimizing heat treatment, or implementing periodic in-service maintenance.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.29-33
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• 2004

Low molecular weight silk fibroin (LMSF), which was prepared by hydrolysis of silk fibroin using high-temperature and high-pressure method, was found to inhibit the oxidation of L-3,4,-dihydroxyphenylalanine (L-DOPA) catalyzed by mushroom tyrosinase (EC 1.14.18.1). LMSF contained mostly free amino acids such as L-glycine, L-alanine, and L-serine and oligopeptides, mainly glycine-alanine dimer. As a result of analyzing the inhibition kinetics from Lineweaver-Burk plots, L-glycine and glycine-alanine dimer showed noncompetitive behavior while uncompetitive behavior was observed in L-alanine, and L-serine. When weight percent concentration of ${ID_50}$ was compared, L-glycine was most effective on the inhibition and LMSF was also good enough for the inhibition effect of tyrosinase activity. LMSF showed a mixed-type inhibition and the inhibitory mechanism of LMSF might be caused by free amino acids and oligopeptides. As a result of spectroscopic observation with time, initial rate of increase of DOPAchrome decreased remarkably and the time to reach maximum absorbance increased as an increase of the concentration of L-glycine, meaning that L-glycine made itself mainly responsible for the formation of chelate with ${Cu^2+}$ in tyrosinase. However, in case of L-alanine, L-serine, and especially glycine-alanine dimmer, the production of DOPAchrome after an arrival at maximum absorbance decreased, indicating the production of adducts through the reaction with DOPAquinone.

• Journal of Animal Science and Technology
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• v.54 no.6
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• pp.395-400
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• 2012

This study was conducted to estimate the growth curve parameters for the body weight (BW) and body length (BL) of miniature pigs in Korea. Growth curve parameters were estimated through a nonlinear regression model using Gompertz, Logistic, and von Bertalanffy methods. A total of 25 piglets were measured monthly from birth up to 15 months of age to estimate both body weight and length. Results showed that the estimated average values for the body weight (body length) were 31.83 kg (58.77 cm) for the mature weight (A), 3.06 (1.74) for the growth ratio (${\beta}$), and 0.28 (0.52) for the maturing rate (${\kappa}$). Average inflection points showing maximum growth rate estimated each month for body weight were 3.97 kg and 11.70 cm, while for the body length were 1.06 kg and 21.61 cm. Moreover, the estimated maturation rates of the body weight and length for the group of Sire 1 were 0.22 and 0.40 respectively, whereas for the group of Sire 2 these values were 0.34 and 0.39. On the other hand, for the groups of Dam 1, Dam 2, and Dam 3, maturation rates for their body weights were 0.26, 0.28 and 0.33 respectively, while for their body lengths these values were 0.43, 0.37, and 0.38, respectively. The study also indicated a negative relationship between the values of mature weight and maturity rate for the body weight will result to a higher inflection point which is in contrast for the body length where results show that a positive relationship between the values of mature length and the maturity rate will result to a higher inflection point. Furthermore, the growth performance of miniature pig varies across stages but using these estimated growth curve parameters could improve the genetic traits of miniature pig.

• Bulletin of the Korean Chemical Society
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• v.32 no.11
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• pp.3967-3972
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• 2011

A whole body physiologically based pharmacokinetic (PBPK) model was applied to investigate absorption, distribution, and physiologic variations on pharmacokinetics of imatinib in human body. Previously published pharmacokinetic data of the drug after intravenous (i.v.) infusion and oral administration were simulated by the PBPK model. Oral dose absorption kinetics were analyzed by adopting a compartmental absorption and transit model in gut section. Tissue/plasma partition coefficients of drug after i.v. infusion were also used for oral administration. Sensitivity analysis of the PBPK model was carried out by taking parameters that were commonly subject to variation in human. Drug concentration in adipose tissue was found to be higher than those in other tissues, suggesting that adipose tissue plays a role as a storage tissue for the drug. Variations of metabolism in liver, body weight, and blood/plasma partition coefficient were found to be important factors affecting the plasma concentration profile of drug in human body.

• Journal of Industrial Technology
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• v.21 no.B
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• pp.27-30
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• 2001

For the development of a large-scale dialysis process for silk fibroin solution, a batch and continuous dialysis chamber was designed and built, which are to be used as a unit module for the process. A series of dialysis experiments were carried out to estimate the kinetic parameters for dialysis using the solutions of salt-solubilized silk fibroin. The solution was dialyzed by distilled water either batch-wise or continuously. Dialysis kinetics was monitored by measuring refractometery at high salt concentration and conductivity at lower salt concentration. The apparent dialysis coefficients were $5.4g/m^2-hr$ and $1.8g/m^2-hr$, for well mixed batch and continuous dialysis, respectively. The alteration of molecular weight distribution of dialyzed silk fibroin solution was monitored.